The API for periodic health checks is repetitive, with a distinct
function for polling a checker to each kind of updater. It also gives
the user no control over the lifetime of the polling goroutines nor
which context is passed into the checker.
Replace the existing PeriodicXYZChecker functions with a single Poll
function which composes an Updater with a Checker. Its context parameter
is passed into the checker and also controls when the polling loop
terminates. To guard against health checks failing closed (ostensibly
healthy) when the polling loop is terminated, the updater is forcefully
updated to an error status, overriding any configured threshold.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Allow health checkers to abort if the request context is canceled.
Modify the checkers to respect context cancelation and return wrapped
errors so the caller of CheckStatus() would be able to discriminate true
failed checks from checks which were aborted because the context became
done.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Our context package predates the establishment of current best practices
regarding context usage and it shows. It encourages bad practices such
as using contexts to propagate non-request-scoped values like the
application version and using string-typed keys for context values. Move
the package internal to remove it from the API surface of
distribution/v3@v3.0.0 so we are free to iterate on it without being
constrained by compatibility.
Signed-off-by: Cory Snider <csnider@mirantis.com>
gofumpt (https://github.com/mvdan/gofumpt) provides a supserset of `gofmt` / `go fmt`,
and addresses various formatting issues that linters may be checking for.
We can consider enabling the `gofumpt` linter to verify the formatting in CI, although
not every developer may have it installed, so for now this runs it once to get formatting
in shape.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Go 1.13 and up enforce import paths to be versioned if a project
contains a go.mod and has released v2 or up.
The current v2.x branches (and releases) do not yet have a go.mod,
and therefore are still allowed to be imported with a non-versioned
import path (go modules add a `+incompatible` annotation in that case).
However, now that this project has a `go.mod` file, incompatible
import paths will not be accepted by go modules, and attempting
to use code from this repository will fail.
This patch uses `v3` for the import-paths (not `v2`), because changing
import paths itself is a breaking change, which means that the
next release should increment the "major" version to comply with
SemVer (as go modules dictate).
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This fixes registry endpoints to return the proper `application/json`
content-type for JSON content, also updating spec examples for that.
As per IETF specification and IANA registry [0], the `application/json`
type is a binary media, so the content-type label does not need any
text-charset selector. Additionally, the media type definition
explicitly states that it has no required nor optional parameters,
which makes the current registry headers non-compliant.
[0]: https://www.iana.org/assignments/media-types/application/json
Signed-off-by: Luca Bruno <lucab@debian.org>
Also, add timeout and status code parameters to the HTTP checker, and
remove the threshold parameter for the file checker.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Update docs.
Change health_test.go tests to create their own registries and register
the checks there. The tests now call CheckStatus directly instead of
polling the HTTP handler, which returns results from the default
registry.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Add a section to the config file called "health". Within this section,
"filecheckers" and "httpcheckers" list checks to run. Each check
specifies a file or URI, a time interval for the check, and a threshold
specifying how many times the check must fail to reach an unhealthy
state.
Document the new options in docs/configuration.md.
Add unit testing for both types of checkers. Add an UnregisterAll
function in the health package to support the unit tests, and an
Unregister function for consistency with Register.
Fix a string conversion problem in the health package's HTTP checker.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Because health check errors may expose sensitive data, we shouldn't expose the
details of the failure to clients. Instead, an error is returned to the client
with a hint about where they could find further information on why the service
is down.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
To ensure the ensure the web application is properly operating, we've added a
periodic health check for the storage driver. If the health check fails three
times in a row, the registry will serve 503 response status for any request
until the condition is resolved. The condition is reported in the response body
and via the /debug/health endpoint.
To ensure that all drivers will properly operate with this health check, a
function has been added to the driver testsuite.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
