failing to send authenticate to opendap url

[Folkes, Michael (DFO/MPO)]

Unclassified - Non-Classifié

Hello,

I’ve been using some R code to annually query opendap for several years.  It worked fine this time last year but I think my problem might be with sending my authentication.

 

I know my url is fine as if I paste it:

https://opendap.earthdata.nasa.gov/collections/C2098858642-POCLOUD/granules/oscar_currents_final_20220101.dap.nc4?dap4.ce=/lon%5B720:1:960%5D;/time%5B0:1:0%5D;/u%5B0:1:0%5D%5B720:1:960%5D%5B519:1:599%5D;/lat%5B519:1:599%5D;/v%5B0:1:0%5D%5B720:1:960%5D%5B519:1:599%5D

 

to the dap4 data request form:

https://opendap.earthdata.nasa.gov/collections/C2098858642-POCLOUD/granules/oscar_currents_final_20220101.dmr.html

(after logging in), it produces the expected data.

 

 

However, sending the same request via R:

httr::GET(url, httr::authenticate(opendap_authenticate$id,opendap_authenticate$pw),httr::write_disk(path = "oscar_currents_final_20220101.nc" , overwrite = TRUE))

 

is producing a “status 401” result.   The ID and PW I send are the same I used to log into the dap4 data request form.

Do you have any suggestions as to why my ID and PW might not be giving me access when I attempt this using a call from R? (again, it worked fine last summer).

Thanks!

Michael

[Miguel Jimenez]

Hi Michael, 

That sounds frustrating. I am very versed in R, but I tried it in python and had no trouble downloading data from that granule. Here is my snippet of code, which uses python's requests session to authenticate

```python

from requests import Session

url = "https://opendap.earthdata.nasa.gov/collections/C2098858642-POCLOUD/granules/oscar_currents_final_20220101.dap?dap4.ce=/lon%5B720:1:960%5D;/time%5B0:1:0%5D;/u%5B0:1:0%5D%5B720:1:960%5D%5B519:1:599%5D;/lat%5B519:1:599%5D;/v%5B0:1:0%5D%5B720:1:960%5D%5B519:1:599%5D"

my_session = Session()

r = my_session.get(url, stream=True)

r.status_code

>>> 200 # <-------- success!

```

NOTE: Python's requests session can discover /recover all the authentication credentials stored in a local `.netrc` file so there is no need to pass these all the time. I know in R one can do that, but it may require configuring R to use curl which is pretty good and efficient. But again, I am not very well versed on that.

That said, I do not know what changed in the year that you have tried it. I know EDL requires updating token credentials every few months (tokens expire in a few months that is), but it looks like you are using username/password and not tokens (unless you have something configured running in the background).

I would suggest looking into configuring R to use .netrc files. THese have pretty strong support and can be used with edl tokens (faster performance, but may require updating the .netrc file every couple of months).

Here is a R resource I found on google : https://docs.posit.co/rspm/user/configure-r.html#configure-r-to-use-netrc-and-curl

Hope this helps, and let me know how it goes!

Miguel