sql: add troubleshooting mode session variable

[THardy98]

Resolves: #84429

This change introduces a troubleshooting_mode_enabled session
variable. When enabled, this session variable is intended to be used as
a way to avoid performing additional work on queries, particularly when
the cluster is experiencing issues/unavailability/failure. By default,
this session variable is disabled. Currently, this session variable is
only used to avoid collecting/emitting telemetry data.

Release note (sql change): Introduce new troubleshooting_mode_enabled
session variable, to avoid doing additional work on queries when
possible (i.e. collection telemetry data). By default, this session
variable is disabled.

[cockroach-teamcity]

This change is 

[knz]

Since the value is already on/off you could name this troubleshooting_mode - the suffix _enabled is unnecessary in this case.

Also, it would be useful to hook this up to the behavior of cockroach sql --debug-sql-cli (see DebugMode in cli/clisqlclient/context.go)

Reviewed 8 of 8 files at r1, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @THardy98)

[THardy98]

Renamed to troubleshooting_mode.

I've added a conditional to enable troubleshooting_mode if the DebugMode flag is set to true at configurePreShellDefaults, once we've parsed the CLI flags. Not sure if this is the best place to do this.

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @knz)

[knz]

Reviewed 9 of 9 files at r2, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @THardy98)

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pkg/cli/clisqlshell/sql.go line 2107 at r2 (raw file):

	}

	if c.sqlConnCtx.DebugMode {

you can put this logic inside a function alongside the others in clisqlcfg/context.go (maybeSetSafeUpdates etc) then call it from Run.

Then you can also add a test for this inside cli/interactive_tests/test_client_side_checking.tcl alongside the others that test the CLI flag.
For example, below the existing prompt expect:

send "show troubleshooting_mode\r"
eexpect "on"
eexpect "root@"

[THardy98]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @knz)

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pkg/cli/clisqlshell/sql.go line 2107 at r2 (raw file):

Previously, knz (kena) wrote…

you can put this logic inside a function alongside the others in clisqlcfg/context.go (maybeSetSafeUpdates etc) then call it from Run.

Then you can also add a test for this inside cli/interactive_tests/test_client_side_checking.tcl alongside the others that test the CLI flag.
For example, below the existing prompt expect:

send "show troubleshooting_mode\r"
eexpect "on"
eexpect "root@"

moved logic to maybeSetTroubleshootingMode, called from Run

added the suggested test to cli/interactive_tests/test_client_side_checking.tcl

[knz]

Reviewed 3 of 3 files at r3, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @THardy98)

---

pkg/cli/clisqlcfg/context.go line 259 at r3 (raw file):

func (c *Context) maybeSetTroubleshootingMode(conn clisqlclient.Conn) error {
	// If we are in debug mode, enable "troubleshooting mode".
	if c.ConnCtx.DebugMode {

easier on the eye:

if !cond { return nil }
return dothething()

---

pkg/cli/interactive_tests/test_client_side_checking.tcl line 100 at r3 (raw file):

# Check that troubleshooting mode is enabled in debug mode.
send "show troubleshooting_mode\r"

this is not the correct place - the test has exited the sql client already above.

[THardy98]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @knz)

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pkg/cli/clisqlcfg/context.go line 259 at r3 (raw file):

Previously, knz (kena) wrote…

easier on the eye:

if !cond { return nil }
return dothething()

Done.

---

pkg/cli/interactive_tests/test_client_side_checking.tcl line 100 at r3 (raw file):

Previously, knz (kena) wrote…

this is not the correct place - the test has exited the sql client already above.

Oops, moved earlier.

[knz]

with nit

Reviewed 1 of 2 files at r4, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @knz and @THardy98)

---

pkg/cli/interactive_tests/test_client_side_checking.tcl line 91 at r4 (raw file):

# Check that troubleshooting mode is enabled in debug mode.
send "show troubleshooting_mode\r"

you still need to wait for the prompt before sending the command (eexpect "root@" just before)

[THardy98]

Reviewable status: complete! 0 of 0 LGTMs obtained (and 1 stale) (waiting on @knz)

---

pkg/cli/interactive_tests/test_client_side_checking.tcl line 91 at r4 (raw file):

Previously, knz (kena) wrote…

you still need to wait for the prompt before sending the command (eexpect "root@" just before)

Done.

[THardy98]

TYFR :)

[THardy98]

bors r+

[craig]

Build succeeded:

• GitHub CI (Cockroach)

[THardy98]

blathers backport 22.1 21.2

[blathers-crl]

Encountered an error creating backports. Some common things that can go wrong:

1. The backport branch might have already existed.
2. There was a merge conflict.
3. The backport branch contained merge commits.

You might need to create your backport manually using the backport tool.

---

error creating merge commit from fd39cd3 to blathers/backport-release-22.1-84452: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 22.1 failed. See errors above.

---

error creating merge commit from fd39cd3 to blathers/backport-release-21.2-84452: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 21.2 failed. See errors above.

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