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feat(mongodb): allow running as single member replicat set #528

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210 changes: 134 additions & 76 deletions nix/services/mongodb.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -48,86 +48,144 @@ in
default = "";
description = "Additional text to be appended to `mongodb.conf`.";
};

replicaSetName = lib.mkOption {
type = types.nullOr types.str;
default = null;
description = "The name of the replica set to configure.";
example = "rs0";
};

ulimit = lib.mkOption {
type = types.nullOr types.ints.unsigned;
default = null;
description = "The maximum number of open file descriptors for mongod.";
};
};

config = {
outputs = {
settings = {
processes = {
"${name}" =
let
mongoConfig = pkgs.writeText "mongodb.conf" ''
net.port: ${toString config.port}
net.bindIp: ${config.bind}
storage.dbPath: ${config.dataDir}
${config.extraConfig}
'';

startScript = pkgs.writeShellApplication {
name = "start-mongodb";
runtimeInputs = [ pkgs.coreutils config.package ];
text = ''
export MONGODATA="${config.dataDir}"

if [[ ! -d "$MONGODATA" ]]; then
mkdir -p "$MONGODATA"
fi
config.outputs.settings.processes =
let
mongoshArgs =
(lib.optional (lib.elem config.bind [ null "0.0.0.0" "::" ]) "--host=${config.bind}")
++
[
"--port=${toString config.port}"
];
mongoshCommand = "${lib.getExe pkgs.mongosh} ${lib.escapeShellArgs mongoshArgs}";
in
{
"${name}" =
let
mongoConfig = pkgs.writeText "mongodb.conf" ''
net.port: ${toString config.port}
net.bindIp: ${config.bind}
storage.dbPath: ${config.dataDir}
${lib.optionalString (config.replicaSetName != null) ''
replication:
replSetName: "${config.replicaSetName}"
''}
${config.extraConfig}
'';

startScript = pkgs.writeShellApplication {
name = "start-mongodb";
runtimeInputs = [ pkgs.coreutils config.package ];
text = ''
export MONGODATA="${config.dataDir}"

if [[ ! -d "$MONGODATA" ]]; then
mkdir -p "$MONGODATA"
fi

${if config.ulimit != null then "ulimit -n ${toString config.ulimit}" else ""}

exec mongod --config "${mongoConfig}"
'';
};
in
{
command = startScript;

readiness_probe = {
exec.command = "${pkgs.mongosh}/bin/mongosh --eval \"db.version()\" > /dev/null 2>&1";
initial_delay_seconds = 2;
period_seconds = 10;
timeout_seconds = 4;
success_threshold = 1;
failure_threshold = 5;
};

# https://github.com/F1bonacc1/process-compose#-auto-restart-if-not-healthy
availability = {
restart = "on_failure";
max_restarts = 5;
};
};
"${name}-configure" =
let
configScript = pkgs.writeShellApplication {
name = "configure-mongo";
text = ''
if ! test -e "${config.dataDir}/.auth_configured"; then
${pkgs.mongosh}/bin/mongosh <<EOF
use admin
db.createUser({
user: "${config.user}",
pwd: "${config.password}",
roles: [
{ role: "userAdminAnyDatabase", db: "admin" },
{ role: "dbAdminAnyDatabase", db: "admin" },
{ role: "readWriteAnyDatabase", db: "admin" }
]
})
EOF
touch "${config.dataDir}/.auth_configured"
else
echo "Database previously configured. If this is in error, remove"
echo "the file at '${config.dataDir}/.auth_configured' and restart"
echo "this process."
exec mongod --config "${mongoConfig}"
'';
};
in
{
command = startScript;

readiness_probe = {
exec.command = "${mongoshCommand} --eval 'db.version()' > /dev/null 2>&1";
initial_delay_seconds = 2;
period_seconds = 10;
timeout_seconds = 4;
success_threshold = 1;
failure_threshold = 5;
};

# https://github.com/F1bonacc1/process-compose#-auto-restart-if-not-healthy
availability = {
restart = "on_failure";
max_restarts = 5;
};
};
"${name}-configure" =
let
replSetConfig = ''{ _id: "${config.replicaSetName}", members: [ { _id: 0, host: "${config.bind}:${toString config.port}" } ] }'';
configScript = pkgs.writeShellApplication {
name = "configure-mongo";
text = ''
${lib.optionalString (config.replicaSetName != null) ''
# Configure replica set
echo "Configuring replica set ${config.replicaSetName}..."

# Check if replica set is already configured
if ! ${mongoshCommand} --eval 'try { rs.status().ok } catch (e) { quit(10) }' --quiet; then
# try initiate, which will fail if already initiated, in which case we reconfig with force:true in case host\port changes
${mongoshCommand} --eval 'try { rs.initiate(${replSetConfig}) } catch (e) { rs.reconfig(${replSetConfig}, { force: true }) }'

echo "Waiting for replica set to stabilize..."
success=0
for i in $(seq 1 30); do
# Try to check if this node has become primary.
# rs.isMaster().ismaster returns true if primary, false otherwise.
# If the command fails (e.g. server not ready), mongosh will exit with a non-zero code due to quit(10).
if ${mongoshCommand} --eval 'try { if (rs.isMaster().ismaster) { quit(0) } else { quit(1) } } catch (e) { quit(10) }' --quiet; then
echo "Replica set primary is active."
success=1
break
fi
echo "Attempt $i/30: Replica set not yet stable, retrying in 1 seconds..."
sleep 1
done

if [[ $success -eq 0 ]]; then
echo "Error: Replica set did not stabilize after 30 seconds."
exit 1
fi
'';
};
in
{
command = configScript;
depends_on."${name}".condition = "process_healthy";
};
else
echo "Replica set ${config.replicaSetName} already configured."
fi
''}

# Configure user
if ! test -e "${config.dataDir}/.auth_configured"; then
${mongoshCommand} <<EOF
use admin
db.createUser({
user: "${config.user}",
pwd: "${config.password}",
roles: [
{ role: "userAdminAnyDatabase", db: "admin" },
{ role: "dbAdminAnyDatabase", db: "admin" },
{ role: "readWriteAnyDatabase", db: "admin" }
]
})
EOF
touch "${config.dataDir}/.auth_configured"
else
echo "Database previously configured. If this is in error, remove"
echo "the file at '${config.dataDir}/.auth_configured' and restart"
echo "this process."
fi
'';
};
in
{
command = configScript;
depends_on."${name}".condition = "process_healthy";
};
};
};
};
}
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