[gdal-dev] errors using IAM instance profile auth in s3

Sun Nov 20 10:20:28 PST 2022

Cool, I was looking at the PR and trying to decide if it was the same error. The error state being cleared and then working did sound like the same issue. It all makes sense now. Thanks for the fix!

Mike

-- 

Michael Smith

US Army Corps / Remote Sensing GIS Center

From: Even Rouault <even.rouault at spatialys.com>
Date: Sunday, November 20, 2022 at 12:52 PM
To: Michael Smith <michael.smith.erdc at gmail.com>
Cc: gdal-dev <gdal-dev at lists.osgeo.org>
Subject: Re: [gdal-dev] errors using IAM instance profile auth in s3

Mike,

I've ended up firing a EC2 instance and I did replicate with my private bucket too.

With a EC2 Ubuntu 22.04 instance, on a minimal GDAL master debug build, things work fine with IAM authentication, in the VM itself

But if I run inside a ubuntu:22.04 Docker image the same build (mounting my home directory), then I got exactly the same symptoms as you!

I finally figured out that the "curl -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 10" request for IDMSv2 was failing inside Docker but not in the outside EC2 VM. Known (intended) issue according to https://community.grafana.com/t/imdsv2-is-not-working-from-docker/65944 

The solution/workaround is to run docker with --network=host (I guess it could be possible to restrict it a bit to just 169.254.169.254)

In https://github.com/OSGeo/gdal/pull/6752, I've pushed a proper fix, that makes sure that the fallback to IDMSv1 works by clearing the GDAL error state (which was the reason for the weird behaviour that GDALOpen() only worked the second time), and emits a hopefully debug hint when it sees that IDMSv2 fails on timeout inside a Docker container.

With the fix, when trying inside a Docker with default networking rules:

# gdalinfo /vsis3/XXXXXXX/byte.tif --debug on
AWS: AWS_ROLE_ARN configuration option not defined
HTTP: Fetch(http://169.254.169.254/latest/api/token)
HTTP: libcurl/7.81.0 GnuTLS/3.7.3 zlib/1.2.11 brotli/1.0.9 zstd/1.4.8 libidn2/2.3.2 libpsl/0.21.0 (+libidn2/2.3.2) libssh/0.9.6/openssl/zlib nghttp2/1.43.0 librtmp/2.3 OpenLDAP/2.5.13
HTTP: Fetch(http://169.254.169.254/latest/meta-data)
S3: /latest/api/token EC2 IDMSv2 request timed out, but /latest/metadata succeeded. Trying with IDMSv1. Try running your Docker container with --network=host.
HTTP: Fetch(http://169.254.169.254/latest/meta-data/iam/security-credentials/)
HTTP: Fetch(http://169.254.169.254/latest/meta-data/iam/security-credentials/ec2_s3)
AWS: Storing AIM credentials until 2022-11-20T23:38:10Z
S3: Switching to region eu-central-1
S3: Downloading 0-1796 (https://XXXXXXX.s3.amazonaws.com/byte.tif)...
S3: Got response_code=206
GDAL: GDALOpen(/vsis3/XXXXXXX/byte.tif, this=0x5599cfbce470) succeeds as GTiff.

It was an "interesting" bug...

Even

Le 20/11/2022 à 14:47, Michael Smith a écrit :

Is there a reason why OpenEx would work but Open wouldn’t?

In [1]: from osgeo import gdal

In [2]: pszFilename = "/vsis3/grid-dev-publiclidar/estonia/dtm/estonia_dtm_5m.tif"

In [3]: hDataset = gdal.Open(pszFilename, gdal.GA_ReadOnly)

In [4]: hDataset

In [5]: hDataset = gdal.OpenEx(pszFilename, gdal.GA_ReadOnly)

In [6]: hDataset

Out[6]: <osgeo.gdal.Dataset; proxy of <Swig Object of type 'GDALDatasetShadow *' at 0x7f827217c450> >

In [7]: hDataset.GetGeoTransform()

Out[7]: (365000.0, 5.0, 0.0, 6635000.0, 0.0, -5.0)

Mike

From: Even Rouault <even.rouault at spatialys.com>
Date: Saturday, November 19, 2022 at 10:08 AM
To: <michael.smith.erdc at gmail.com>
Cc: gdal-dev <gdal-dev at lists.osgeo.org>
Subject: Re: [gdal-dev] errors using IAM instance profile auth in s3

Le 19/11/2022 à 16:00, michael.smith.erdc at gmail.com a écrit :

Correct, not a public bucket, which is why the IAM credentials are needed. If I set them manually, it all works fine.

That's super weird if the result of a range request changes depending on how credentials have been set... Perhaps enable CPL_CURL_VERBOSE=ON env variable and diff the logs ?

You could also try the gdal_cp.py sample script at https://github.com/OSGeo/gdal/blob/master/swig/python/gdal-utils/osgeo_utils/samples/gdal_cp.py , which is a cp-like utility working with GDAL virtual file systems, with the 2 authentication methods

python gdal_cp.py /vsis3/grid-dev-publiclidar/estonia/dtm/estonia_dtm_5m.tif out.tif

(you can interrupt it with ctrl-c after a few seconds. that will be enough to get the first bytes)

you might need to run an hexadecimal editor to inspect a bit the content.

[ u02]$ export AWS_ACCESS_KEY_ID=xxxxx

Yes, a 206 response code means success here as we are requesting only bytes 0-16383. So maybe the file is not a valid TIFF ?

( "grid-dev-publiclidar" must not be so public I guess, because when trying with my credentials, I get a Access Denied)

Le 19/11/2022 à 15:40, michael.smith.erdc at gmail.com a écrit :

I’m seeing that it’s getting a 206 response code, so wouldn’t that indicate auth is working? 

 gdalinfo /vsis3/grid-dev-publiclidar/estonia/dtm/estonia_dtm_5m.tif

HTTP: Fetch(http://169.254.169.254/latest/api/token)

HTTP: libcurl/7.86.0 OpenSSL/3.0.7 zlib/1.2.13 libssh2/1.10.0 nghttp2/1.47.0

HTTP: These HTTP headers were set: X-aws-ec2-metadata-token-ttl-seconds: 10

HTTP: Fetch(http://169.254.169.254/latest/meta-data/iam/security-credentials/)

HTTP: Fetch(http://169.254.169.254/latest/meta-data/iam/security-credentials/iam-grid-s3)

AWS: Storing AIM credentials until 2022-11-19T20:42:58Z

S3: Downloading 0-16383 (https://grid-dev-publiclidar.s3.amazonaws.com/estonia/dtm/estonia_dtm_5m.tif)...

S3: Got response_code=206

gdalinfo failed - unable to open '/vsis3/grid-dev-publiclidar/estonia/dtm/estonia_dtm_5m.tif'.

Mike

On Nov 19, 2022, at 9:26 AM, Even Rouault <even.rouault at spatialys.com> wrote:

Hi Mike,

could you send the output of

curl http://169.254.169.254/latest/meta-data/iam/security-credentials/iam-grid-s3

Slightly redacted of course, but with the exact formatting. This part of thee code currently uses a "simple JSON parser" (https://github.com/OSGeo/gdal/blob/c61d116a469821b769630a112dee7f1a61fed885/port/cpl_aws.cpp#L554), which is actually just a non JSON-aware string tokenizer, and I suspect it could be defeated by a new formatting of S3 or something specific to your credentials.

It could also be that something unhandled by that parser appears inside quoted strings, like an escaped double quote or some other JSON escaped character (like an escaped forward slash \/ )

If that was the case we should likely switch to proper JSON deserialization (that part of the code must predate libjson-c being a build requirement of GDAL).

Even

-- 
http://www.spatialys.com
My software is free, but my time generally not.
-- 
http://www.spatialys.com
My software is free, but my time generally not.
-- 
http://www.spatialys.com
My software is free, but my time generally not.
-- 
http://www.spatialys.com
My software is free, but my time generally not.

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