Consul provides a feature of Service Definitions where the tags
associated with a service can be modified through the Catalog API,
overriding the value(s) configured in the agent's service configuration.
To enable this feature, the flag enable_tag_override must be configured
in the service definition.
Previously, Nomad did not allow configuring this flag, and thus the default
value of false was used. Now, it is configurable.
Because Nomad itself acts as a state machine around the the service definitions
of the tasks it manages, it's worth describing what happens when this feature
is enabled and why.
Consider the basic case where there is no Nomad, and your service is provided
to consul as a boring JSON file. The ultimate source of truth for the definition
of that service is the file, and is stored in the agent. Later, Consul performs
"anti-entropy" which synchronizes the Catalog (stored only the leaders). Then
with enable_tag_override=true, the tags field is available for "external"
modification through the Catalog API (rather than directly configuring the
service definition file, or using the Agent API). The important observation
is that if the service definition ever changes (i.e. the file is changed &
config reloaded OR the Agent API is used to modify the service), those
"external" tag values are thrown away, and the new service definition is
once again the source of truth.
In the Nomad case, Nomad itself is the source of truth over the Agent in
the same way the JSON file was the source of truth in the example above.
That means any time Nomad sets a new service definition, any externally
configured tags are going to be replaced. When does this happen? Only on
major lifecycle events, for example when a task is modified because of an
updated job spec from the 'nomad job run <existing>' command. Otherwise,
Nomad's periodic re-sync's with Consul will now no longer try to restore
the externally modified tag values (as long as enable_tag_override=true).
Fixes#2057
This change provides an initial pass at setting up the configuration necessary to
enable use of Connect with Consul ACLs. Operators will be able to pass in a Consul
Token through `-consul-token` or `$CONSUL_TOKEN` in the `job run` and `job revert`
commands (similar to Vault tokens).
These values are not actually used yet in this changeset.
copy struct values
ensure groupserviceHook implements RunnerPreKillhook
run deregister first
test that shutdown times are delayed
move magic number into variable
The existing version constraint uses logic optimized for package
managers, not schedulers, when checking prereleases:
- 1.3.0-beta1 will *not* satisfy ">= 0.6.1"
- 1.7.0-rc1 will *not* satisfy ">= 1.6.0-beta1"
This is due to package managers wishing to favor final releases over
prereleases.
In a scheduler versions more often represent the earliest release all
required features/APIs are available in a system. Whether the constraint
or the version being evaluated are prereleases has no impact on
ordering.
This commit adds a new constraint - `semver` - which will use Semver
v2.0 ordering when evaluating constraints. Given the above examples:
- 1.3.0-beta1 satisfies ">= 0.6.1" using `semver`
- 1.7.0-rc1 satisfies ">= 1.6.0-beta1" using `semver`
Since existing jobspecs may rely on the old behavior, a new constraint
was added and the implicit Consul Connect and Vault constraints were
updated to use it.
If a websocket connection errors we currently return the error with a
copy of the response body. The response body from the websocket can
often times be completely illegible so remove it from the error string.
make alloc id empty for more reliable failure
un-gzip if content encoding header present
Jobs can be created with user-provided IDs containing any character
except spaces. The jobId needs to be escaped when used in a request
path, otherwise jobs created with names such as "why?" can't be managed
after they are created.
This commit introduces support for configuring mount propagation when
mounting volumes with the `volume_mount` stanza on Linux targets.
Similar to Kubernetes, we expose 3 options for configuring mount
propagation:
- private, which is equivalent to `rprivate` on Linux, which does not allow the
container to see any new nested mounts after the chroot was created.
- host-to-task, which is equivalent to `rslave` on Linux, which allows new mounts
that have been created _outside of the container_ to be visible
inside the container after the chroot is created.
- bidirectional, which is equivalent to `rshared` on Linux, which allows both
the container to see new mounts created on the host, but
importantly _allows the container to create mounts that are
visible in other containers an don the host_
private and host-to-task are safe, but bidirectional mounts can be
dangerous, as if the code inside a container creates a mount, and does
not clean it up before tearing down the container, it can cause bad
things to happen inside the kernel.
To add a layer of safety here, we require that the user has ReadWrite
permissions on the volume before allowing bidirectional mounts, as a
defense in depth / validation case, although creating mounts should also require
a priviliged execution environment inside the container.
