Fault-tolerant and highly-available configuration of distributed services

One or more non-transitory computer-readable media storing one or more programs for execution by one or more processors, the one or more programs comprising instructions for:

• setting a watch on a first key in a first replica of a distributed configuration store;
• setting a value of a second key in a second replica of the distributed configuration store, the value of the second key indicating that a first sub-task of a distributed task is successfully complete;
• wherein the second replica comprises the first key;
• wherein the value of the second key set in the second replica is replicated from the second replica to the first replica based at least in part on a consensus protocol;
• wherein the first replica and the second replica are stored at different hosts;
• based, at least in part, on the watch set on the first key, receiving the value of the second key from the first replica;
• and
• based, at least in part, on the receiving the value of the second key from the first replica, initiating execution of a second sub-task of the distributed task that is dependent on successful completion of the first sub-task.

A system, comprising:

• one or more processors;
• one or more storage media storing one or more programs for execution by the one or more processors, the one or more programs comprising instructions for:
• setting a watch on a first key in a first replica of a distributed configuration store;
• setting a value of a second key in a second replica of the distributed configuration store, the value of the second key indicating that a first sub-task of a distributed task is successfully complete;
• wherein the second replica comprises the first key;
• wherein the value of the second key set in the second replica is replicated from the second replica to the first replica based at least in part on a consensus protocol;
• wherein the first replica and the second replica are stored at different hosts;
• based, at least in part, on the watch set on the first key, receiving the value of the second key from the first replica;
• and
• based, at least in part, on the receiving the value of the second key from the first replica, initiating execution of a second sub-task of the distributed task that is dependent on successful completion of the first sub-task.