Propose a command that amalgamates cmd+test+archive-logs

rfcs/store-results.md

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+# Add a command to store the results of command/query execution
+
+While participating in a support escalation on a Kubernetes cluster, it
+struck me how tedious and error-prone it was to execute queries across
+nodes on the cluster and copy the results out for further analysis.
+
+TPA has some pieces that could make this easier for its clusters:
+
+* `tpaexec cmd` executes ad-hoc commands (including via `-m script`),
+  and `tpaexec playbook` executes playbooks.
+
+* `tpaexec test` and other commands like `archive-logs` already know how
+  to copy things from the instances and store them in local directories
+
+We could put these together into a slightly different form and provide a
+command like the following:
+
+    tpaexec execute mycluster \
+        [--commands-from … | --queries-from … | --script …]
+
+This would execute the given input on all applicable instances (and we
+could support `--hosts role_xyz:!role_pqr` as well), and create local
+directories in the style of `tpaexec test` and store the output there,
+with unambiguous hostnames and timestamps.
+
+Or perhaps we could have separate commands:
+
+    tpaexec execute-script mycluster xyz.sh
+    tpaexec execute-queries mycluster xyz.sql
+
+(We don't need to do anything for playbooks, because `tpaexec playbook`
+is good enough already.)