OpAMP Agent Extension

[portertech]

Creating this PR for increased visibility, early feedback, and OpAMP server testing. This pull-request supersedes #855.

This OpAMP agent implementation manages a single local configuration file (e.g. opamp-remote-config.yaml) intended to be consumed by the glob configuration provider. The configuration file directory is configurable via remote_configuration_directory, this directory must match the glob configuration provider pattern used by the collector (e.g. remote_configuration_directory: /etc/otelcol-sumo/conf.d -> --config "glob:/etc/otelcol-sumo/conf.d/*"). Remote configuration updates trigger a collector reload via a SIGHUP signal (to self).

Example OpAMP configuration for testing:

extensions:
  sumologic:
    install_token: ${SUMOLOGIC_INSTALL_TOKEN}
    api_base_url: "https://stag-open-events.sumologic.net"
  opamp:
    instance_uid: 01BX5ZZKBKACTAV9WEVGEMMVRZ
    endpoint: "wss://stag-opamp-events.sumologic.net/v1/opamp"
    remote_configuration_directory: /Users/sporter/Desktop/conf.d

./otelcolbuilder/cmd/otelcol-sumo --config /Users/sporter/Desktop/sumologic.yaml --config "glob:/Users/sporter/Desktop/conf.d/*"

[portertech]

This extension is currently able to authenticate to our OpAMP server and send a mock effective configuration on request. There is a known race condition in regards to authentication.

2022-12-29T15:19:59.994-0800    info    [email protected]/opamp_agent.go:91     Connected to the OpAMP server   {"kind": "extension", "name": "opamp"}
2022-12-29T15:19:59.995-0800    info    [email protected]/opamp_agent.go:100    OpAMP server requested the effective configuration      {"kind": "extension", "name": "opamp"}

The OpAMP server does not yet reply with a remote configuration to apply. If it were to reply with one, the extension's OpAMP agent would produce a new effective configuration and report it to the server. The effective configuration is not yet applied to the collector itself (soon). This work is in a state where it is useful for testing the OpAMP server development.

saw only last commit

[portertech]

@sumo-drosiek I'll definitely call upon you for a review once things stabilize 👍

[perk-sumo]

@portertech one thing that I thing we need is a README, other than that LGTM (as alpha feature that's disabled by default 😉 )

[portertech]

@perk-sumo Is this sufficient? I used the Sumo extension readme as a base.