Motivation

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Deploys a deployment unit with identifier <deployment_unit_id> to the cluster.

$ ignite3 unit deploy <deployment_unit_id> --version <deployment_unit_version> --path <file>|<dir> 

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The deployment unit must be uploaded to the CMG Raft group majority nodes and must include a leader in the current term (Fig. 1 shows an example of such a majority with an included leader but it is not mandatory). It will ensure that the system is able to detect the change of leader and deploy units correctly; the leader is always a part of the majority during the uploading process.

While majority nodes are available there is at least one node which has an uploaded deployment unit and this deployment unit could be deployed on another node on demand. Otherwise the cluster itself can’t operate correctly.

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1. Choose a majority which contains available nodes including a leader.
2. Supplement chosen set of target nodes by user provided nodes if needed.
3. Assign depOpId the meta storage revision number.
4. Create meta storage record for given deployment unit clusterDURecord(depOpId, UPLOADING). This operation could fail because another process has already created a record for the same deployment unit in any status.
5. Initiate uploading of files to the target nodes and create meta storage record for given deployment unit and node nodeDURecord(depOpId, UPLOADING, node).
6. As soon as the deployment unit is uploaded to the node, nodeDURecord.status must be changed to DEPLOYED value - nodeDURecord(depOpId, DEPLOYED, node).
7. As soon as the deployment unit is uploaded to the target nodes, clusterDURecord.status must be changed to DEPLOYED value - clusterDURecord(depOpId, DEPLOYED).

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