forked from TrueCloudLab/restic
5c4653f427
Added an explanation of how to specify the AWS S3 storage classes and what the default value is.
347 lines
12 KiB
ReStructuredText
347 lines
12 KiB
ReStructuredText
..
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Normally, there are no heading levels assigned to certain characters as the structure is
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determined from the succession of headings. However, this convention is used in Python’s
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Style Guide for documenting which you may follow:
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# with overline, for parts
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* for chapters
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= for sections
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- for subsections
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^ for subsubsections
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" for paragraphs
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########
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Examples
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########
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********************************
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Setting up restic with Amazon S3
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********************************
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Preface
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=======
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This tutorial will show you how to use restic with AWS S3. It will show you how
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to navigate the AWS web interface, create an S3 bucket, create a user with
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access to only this bucket, and finally how to connect restic to this bucket.
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Prerequisites
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=============
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You should already have a ``restic`` binary available on your system that you can
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run. Furthermore, you should also have an account with
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`AWS <https://aws.amazon.com/>`__. You will likely need to provide credit card
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details for billing purposes, even if you use their
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`free-tier <https://aws.amazon.com/free/>`__.
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Logging into AWS
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================
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Point your browser to
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https://console.aws.amazon.com
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and log in using your AWS account. You will be presented with the AWS homepage:
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.. image:: images/aws_s3/01_aws_start.png
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:alt: AWS Homepage
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By using the "Services" button in the upper left corder, a menu of all services
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provided by AWS can be opened:
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.. image:: images/aws_s3/02_aws_menu.png
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:alt: AWS Services Menu
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For this tutorial, the Simple Storage Service (S3), as well as Identity and
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Access Management (IAM) are relevant.
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Creating the bucket
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===================
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First, a bucket to store your backups in must be created. Using the "Services"
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menu, navigate to S3. In case you already have some S3 buckets, you will see a
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list of them here:
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.. image:: images/aws_s3/03_buckets_list_before.png
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:alt: List of S3 Buckets
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Click the "Create bucket" button and choose a name and region for your new
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bucket. For the purpose of this tutorial, the bucket will be named
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``restic-demo`` and reside in Frankfurt. Because the bucket name space is
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shared among all AWS users, the name ``restic-demo`` may not be available to
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you. Be creative and choose a unique bucket name.
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.. image:: images/aws_s3/04_bucket_create_start.png
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:alt: Create a Bucket
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It is not necessary to configure any special properties or permissions of the
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bucket just yet. Therefore, just finish the wizard without making any further
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changes:
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.. image:: images/aws_s3/05_bucket_create_review.png
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:alt: Review Bucket Creation
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The newly created ``restic-demo`` bucket will now appear on the list of S3
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buckets:
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.. image:: images/aws_s3/06_buckets_list_after.png
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:alt: List With New Bucket
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Creating a user
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===============
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Use the "Services" menu of the AWS web interface to navigate to IAM. This will
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bring you to the IAM homepage. To create a new user, click on the "Users" menu
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entry on the left:
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.. image:: images/aws_s3/07_iam_start.png
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:alt: IAM Home Page
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In case you already have set-up users with IAM before, you will see a list of
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them here. Use the "Add user" button at the top to create a new user:
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.. image:: images/aws_s3/08_user_list.png
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:alt: IAM User List
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For this tutorial, the new user will be named ``restic-demo-user``. Feel free to
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choose your own name that best fits your needs. This user will only ever access
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AWS through the ``restic`` program and not through the web interface. Therefore,
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"Programmatic access" is selected for "Access type":
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.. image:: images/aws_s3/09_user_name.png
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:alt: Choose User Name and Access Type
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During the next step, permissions can be assigned to the new user. To use this
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user with restic, it only needs access to the ``restic-demo`` bucket. Select
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"Attach existing policies directly", which will bring up a list of pre-defined
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policies below. Afterwards, click the "Create policy" button to create a custom
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policy:
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.. image:: images/aws_s3/10_user_pre_policy.png
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:alt: Assign a Policy
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A new browser window or tab will open with the policy wizard. In Amazon IAM,
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policies are defined as JSON documents. For this tutorial, the "Visual editor"
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will be used to generate a policy:
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.. image:: images/aws_s3/11_policy_start.png
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:alt: Create a New Policy
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For restic to work, two permission statements must be created using the visual
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policy editor. The first statement is set up as follows:
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.. code::
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Service: S3
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Allow Actions: DeleteObject, GetObject, PutObject
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Resources: arn:aws:s3:::restic-demo/*
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This statement allows restic to create, read and delete objects inside the S3
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bucket named ``restic-demo``. Adjust the bucket's name to the name of the
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bucket you created earlier. Next, add a second statement using the "Add
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additional permissions" button:
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.. code::
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Service: S3
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Allow Actions: ListBucket, GetBucketLocation
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Resource: arn:aws:s3:::restic-demo
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Again, substitute ``restic-demo`` with the actual name of your bucket. Note
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that, unlike before, there is no ``/*`` after the bucket name. This statement
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allows restic to list the objects stored in the ``restic-demo`` bucket and to
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query the bucket's region.
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Continue to the next step by clicking the "Review policy" button and enter a
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name and description for this policy. For this tutorial, the policy will be
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named ``restic-demo-policy``. Click "Create policy" to finish the process:
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.. image:: images/aws_s3/13_policy_review.png
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:alt: Policy Review
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Go back to the browser window or tab where you were previously creating the new
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user. Click the button labeled "Refresh" above the list of policies to make
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sure the newly created policy is available to you. Afterwards, use the search
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function to search for the ``restic-demo-policy``. Select this policy using the
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checkbox on the left. Then, continue to the next step.
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.. image:: images/aws_s3/14_user_attach_policy.png
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:alt: Attach Policy to User
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The next page will present an overview of the user account that is about to be
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created. If everything looks good, click "Create user" to complete the process:
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.. image:: images/aws_s3/15_user_review.png
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:alt: User Creation Review
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After the user has been created, its access credentials will be displayed. They
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consist of the "Access key ID" (think user name), and the "Secret access key"
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(think password). Copy these down to a safe place.
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.. image:: images/aws_s3/16_user_created.png
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:alt: User Credentials
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You have now completed the configuration in AWS. Feel free to close your web
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browser now.
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Initializing the restic repository
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==================================
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Open a terminal and make sure you have the ``restic`` binary ready. First, choose
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a password to encrypt your backups with. In this tutorial, ``apg`` is used for
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this purpose:
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.. code-block:: console
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$ apg -a 1 -m 32 -n 1 -M NCL
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I9n7G7G0ZpDWA3GOcJbIuwQCGvGUBkU5
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Note this password somewhere safe along with your AWS credentials. Next, the
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configuration of restic will be placed into environment variables. This will
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include sensitive information, such as your AWS secret and repository password.
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Therefore, make sure the next commands **do not** end up in your shell's
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history file. Adjust the contents of the environment variables to fit your
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bucket's name and your user's API credentials.
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.. code-block:: console
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$ unset HISTFILE
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$ export RESTIC_REPOSITORY="s3:https://s3.amazonaws.com/restic-demo"
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$ export AWS_ACCESS_KEY_ID="AKIAJAJSLTZCAZ4SRI5Q"
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$ export AWS_SECRET_ACCESS_KEY="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"
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$ export RESTIC_PASSWORD="I9n7G7G0ZpDWA3GOcJbIuwQCGvGUBkU5"
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After the environment is set up, restic may be called to initialize the
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repository:
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.. code-block:: console
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$ ./restic init
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created restic backend b5c661a86a at s3:https://s3.amazonaws.com/restic-demo
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Please note that knowledge of your password is required to access
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the repository. Losing your password means that your data is
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irrecoverably lost.
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restic is now ready to be used with AWS S3. Try to create a backup:
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.. code-block:: console
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$ dd if=/dev/urandom bs=1M count=10 of=test.bin
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10+0 records in
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10+0 records out
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10485760 bytes (10 MB, 10 MiB) copied, 0,0891322 s, 118 MB/s
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$ ./restic backup test.bin
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scan [/home/philip/restic-demo/test.bin]
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scanned 0 directories, 1 files in 0:00
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[0:04] 100.00% 2.500 MiB/s 10.000 MiB / 10.000 MiB 1 / 1 items ... ETA 0:00
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duration: 0:04, 2.47MiB/s
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snapshot 10fdbace saved
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$ ./restic snapshots
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ID Date Host Tags Directory
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----------------------------------------------------------------------
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10fdbace 2017-03-26 16:41:50 blackbox /home/philip/restic-demo/test.bin
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A snapshot was created and stored in the S3 bucket. By default backups to AWS S3 will use the ``STANDARD`` storage class. Available storage classes include ``STANDARD``, ``STANDARD_IA``, ``ONEZONE_IA``, ``INTELLIGENT_TIERING``, and ``REDUCED_REDUNDANCY``. A different storage class could have been specified in the above command by using -o or --option:
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.. code-block:: console
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$ ./restic backup -o s3.storageclass=REDUCED_REDUNDANCY test.bin
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This snapshot may now be restored:
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.. code-block:: console
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$ mkdir restore
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$ ./restic restore 10fdbace --target restore
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restoring <Snapshot 10fdbace of [/home/philip/restic-demo/test.bin] at 2017-03-26 16:41:50.201418102 +0200 CEST by philip@blackbox> to restore
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$ ls restore/
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test.bin
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The snapshot was successfully restored. This concludes the tutorial.
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*****************************************************
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Backing up your system without running restic as root
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*****************************************************
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Motivation
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==========
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Creating a complete backup of a machine requires a privileged process
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that is able to read all files. On UNIX-like systems this is
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traditionally the ``root`` user. Processes running as root have
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superpower. They cannot only read all files but do also have the power
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to modify the system in any possible way.
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With great power comes great responsibility. If a process running as
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root malfunctions, is exploited, or simply configured in a wrong way it
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can cause any possible damage to the system. This means you only want
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to run programs as root that you trust completely. And even if you
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trust a program, it is good and common practice to run it with the
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least possible privileges.
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Capabilities on Linux
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=====================
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Fortunately, Linux has functionality to divide root's power into
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single separate *capabilities*. You can remove these from a process
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running as root to restrict it. And you can add capabilities to a
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process running as a normal user, which is what we are going to do.
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Full backup without root
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========================
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To be able to completely backup a system, restic has to read all the
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files. Luckily Linux knows a capability that allows precisely this. We
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can assign this single capability to restic and then run it as an
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unprivileged user.
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First we create a new user called ``restic`` that is going to create
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the backups:
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.. code-block:: console
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root@a3e580b6369d:/# useradd -m restic
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Then we download and install the restic binary into the user's home
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directory.
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.. code-block:: console
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root@a3e580b6369d:/# mkdir ~restic/bin
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root@a3e580b6369d:/# curl -L https://github.com/restic/restic/releases/download/v0.9.1/restic_0.9.1_linux_amd64.bz2 | bunzip2 > ~restic/bin/restic
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Before we assign any special capability to the restic binary we
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restrict its permissions so that only root and the newly created
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restic user can execute it. Otherwise another - possibly untrusted -
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user could misuse the privileged restic binary to circumvent file
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access controls.
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.. code-block:: console
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root@a3e580b6369d:/# chown root:restic ~restic/bin/restic
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root@a3e580b6369d:/# chmod 750 ~restic/bin/restic
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Finally we can use ``setcap`` to add an extended attribute to the
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restic binary. On every execution the system will read the extended
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attribute, interpret it and assign capabilities accordingly.
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.. code-block:: console
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root@a3e580b6369d:/# setcap cap_dac_read_search=+ep ~restic/bin/restic
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From now on the user ``restic`` can run restic to backup the whole
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system.
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.. code-block:: console
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root@a3e580b6369d:/# sudo -u restic /home/restic/bin/restic --exclude={/dev,/media,/mnt,/proc,/run,/sys,/tmp,/var/tmp} -r /tmp backup /
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