78 lines
2.6 KiB
Nix
78 lines
2.6 KiB
Nix
{ curl, targetRoot, wgetExtraOptions }:
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# Note: be very cautious about dependencies, each dependency grows
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# the closure of the initrd. Ideally we would not even require curl,
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# but there is no reasonable way to send an HTTP PUT request without
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# it. Note: do not be fooled: the wget referenced in this script
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# is busybox's wget, not the fully featured one with --method support.
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#
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# Make sure that every package you depend on here is already listed as
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# a channel blocker for both the full-sized and small channels.
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# Otherwise, we risk breaking user deploys in released channels.
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#
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# Also note: OpenStack's metadata service for its instances aims to be
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# compatible with the EC2 IMDS. Where possible, try to keep the set of
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# fetched metadata in sync with ./openstack-metadata-fetcher.nix .
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''
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metaDir=${targetRoot}etc/ec2-metadata
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mkdir -m 0755 -p "$metaDir"
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rm -f "$metaDir/*"
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get_imds_token() {
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# retry-delay of 1 selected to give the system a second to get going,
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# but not add a lot to the bootup time
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${curl}/bin/curl \
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-v \
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--retry 3 \
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--retry-delay 1 \
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--fail \
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-X PUT \
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--connect-timeout 1 \
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-H "X-aws-ec2-metadata-token-ttl-seconds: 600" \
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http://169.254.169.254/latest/api/token
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}
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preflight_imds_token() {
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# retry-delay of 1 selected to give the system a second to get going,
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# but not add a lot to the bootup time
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${curl}/bin/curl \
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-v \
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--retry 3 \
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--retry-delay 1 \
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--fail \
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--connect-timeout 1 \
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-H "X-aws-ec2-metadata-token: $IMDS_TOKEN" \
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http://169.254.169.254/1.0/meta-data/instance-id
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}
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try=1
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while [ $try -le 3 ]; do
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echo "(attempt $try/3) getting an EC2 instance metadata service v2 token..."
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IMDS_TOKEN=$(get_imds_token) && break
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try=$((try + 1))
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sleep 1
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done
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if [ "x$IMDS_TOKEN" == "x" ]; then
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echo "failed to fetch an IMDS2v token."
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fi
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try=1
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while [ $try -le 10 ]; do
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echo "(attempt $try/10) validating the EC2 instance metadata service v2 token..."
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preflight_imds_token && break
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try=$((try + 1))
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sleep 1
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done
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echo "getting EC2 instance metadata..."
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wget_imds() {
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wget ${wgetExtraOptions} --header "X-aws-ec2-metadata-token: $IMDS_TOKEN" "$@";
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}
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wget_imds -O "$metaDir/ami-manifest-path" http://169.254.169.254/1.0/meta-data/ami-manifest-path
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(umask 077 && wget_imds -O "$metaDir/user-data" http://169.254.169.254/1.0/user-data)
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wget_imds -O "$metaDir/hostname" http://169.254.169.254/1.0/meta-data/hostname
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wget_imds -O "$metaDir/public-keys-0-openssh-key" http://169.254.169.254/1.0/meta-data/public-keys/0/openssh-key
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''
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