Initial manager missing infrakit tags

[kaufers]

Flow:

• Bootstrap VM creates initial manager with LogicalID of mgr1 in os group mode with shared NFS for terraform files
• mgr1 then commits a group with the 2 (or 4) additional managers
• group controller detects that mgr1 already exists and issues a Provision for the additional members

The managers group is successfully created with the following members:

+ infrakit group describe managers
ID                            	LOGICAL                       	TAGS
instance-1499453209           	mgr3                          	infrakit-link-context=swarm::rnn3rirgdngoflx2xlmgilzbj::manager,infrakit-link-created=2017-07-07t18:46:47z,infrakit-link=za1pnvookmnx4ylh,infrakit.config_sha=qhzuig2vfziwccsahjlawpwzrdp44gi3,infrakit.group=managers,logicalid=mgr3,name=instance-1499453209,swarm-id=rnn3rirgdngoflx2xlmgilzbj
instance-1499453211           	mgr2                          	infrakit-link-context=swarm::rnn3rirgdngoflx2xlmgilzbj::manager,infrakit-link-created=2017-07-07t18:46:47z,infrakit-link=ynas3ip2mep6z373,infrakit.config_sha=qhzuig2vfziwccsahjlawpwzrdp44gi3,infrakit.group=managers,logicalid=mgr2,name=instance-1499453211,swarm-id=rnn3rirgdngoflx2xlmgilzbj
instance-1499452504           	mgr1                          	infrakit.config_sha=2wrobluhcc7havbj5hlpxfpv6lmwwdzx,infrakit.group=managers,logicalid=mgr1,name=instance-1499452504

Since mgr1 was not created using the swarm flavor it is missing the infrakit-link-context, infrakit-link-created, infrakit-link, and swarm-id tags. Also, the infrakit.config_sha tag is different then the other 2 managers.

The instance SPI has a Label function that can be used to update the tags on mgr1. https://github.com/docker/infrakit/blob/master/pkg/spi/instance/spi.go#L31

@chungers Any ideas on how we can update the tags on mgr1 to make them consistent with the others?

[chungers]

@kaufers - I think if you label the initial manager with a label bootstrap, the group controller will essentially assimilate it and considers it a member of the group and update its labels:

https://github.com/docker/infrakit/blob/master/pkg/plugin/group/scaled.go#L191

convergence: https://github.com/docker/infrakit/blob/master/pkg/plugin/group/scaler.go#L230

[kaufers]

Thanks @chungers; this appeared to update the infrakit.config_sha label on the initial manager correctly.

+ docker exec d4b-instance-plugin infrakit group describe managers
ID                            	LOGICAL                       	TAGS
instance-1501184046           	mgr1                          	infrakit.config_sha=cldtgspin74nag7ytzjlgcl3ne6xlztf,infrakit.group=managers,logicalid=mgr1
instance-1501184432           	mgr3                          	infrakit-link-context=swarm::wa39pil0zk243rq2y285rl69t::manager,infrakit-link-created=2017-07-27t19:40:30z,infrakit-link=jkykcjdir4u7qj6c,infrakit.config_sha=cldtgspin74nag7ytzjlgcl3ne6xlztf,infrakit.group=managers,logicalid=mgr3,name=instance-1501184432,swarm-id=wa39pil0zk243rq2y285rl69t
instance-1501184435           	mgr2                          	infrakit-link-context=swarm::wa39pil0zk243rq2y285rl69t::manager,infrakit-link-created=2017-07-27t19:40:30z,infrakit-link=pnfel8wcfq7uvser,infrakit.config_sha=cldtgspin74nag7ytzjlgcl3ne6xlztf,infrakit.group=managers,logicalid=mgr2,name=instance-1501184435,swarm-id=wa39pil0zk243rq2y285rl69t

However, the initial manager is still different then the others.

• What about the other tags that are missing on mgr1; do they matter?
• What about the fact the there the docker engine on the initial manager does not have any infrakit-* labels?

[chungers]

The config sha is the most important because that's how infrakit determines if the nodes in the group are of the same configuration. The other flags, in particular, the link-context, is a 'join' key that associates a swarm node to an infrastructure node /host. This ideally should be the label for Docker engine on the initial node, but it most certainly isn't, because we wouldn't know what values to set (those are generated by the swarm flavor plugin).

However, these labels can be pre-assigned and set up as the initial Docker engine labels.. For example, we could set it up so that the first node has the infrakit-link-context label set to some known value, say, "bootstrap", as any string value would work as long as the Docker engine and host all have the same values (thus the 'join'). The only other label missing is the swarm id, but that is just informational only and doesn't serve any purposes for infrastructure orchestration and monitoring.